1. Field of the Invention
The present invention relates to optics, more particularly, to an integrated optical auto focus and zooming system.
2. Description of Related Art
In the current optical auto focus and zooming systems, a conventional motor is generally used to drive an optical lens (or lens set) through a transmission mechanism, such that the structure is complex. In addition, since conventional motors have a relatively high rotating speed, mostly, a speed-restraining mechanism is required additionally. As a result, the structure becomes even more complex, and the transmission efficiency of the system is reduced.
Lately ultrasonic motors (e.g., U.S. Pat. No. 6,940,209) that utilize the reverse piezoelectric effect of piezoelectric materials and a driving mechanism formed by a specific design are adopted, which consist of only functional members such as a stator and a rotor with piezoelectric elements fixed on the stator. Since ultrasonic motors have the advantages of low rotating speed and simple transmission mechanism, they provide a good alternative for driving the optical auto focus and zooming system.
However, when an optical lens is driven by the torque output from an ultrasonic motor via the motor shaft, transmission parts and/or connection parts are required additionally to transfer the torque to the lens, leading to the following disadvantages: first, the structural complexity is increased; second, the fabricating cost is increased; and third, the precision, the stability, and the reliability of the operation of the optical lens are greatly limited by the transmission parts or by the connection parts.